U.S. patent application number 11/634294 was filed with the patent office on 2007-11-22 for multi-domain vertically aligned liquid crystal display device.
This patent application is currently assigned to WINTEK CORPORATION. Invention is credited to Chien-Chung Kuo, Chin-Chang Liu.
Application Number | 20070268435 11/634294 |
Document ID | / |
Family ID | 38292357 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070268435 |
Kind Code |
A1 |
Kuo; Chien-Chung ; et
al. |
November 22, 2007 |
Multi-domain vertically aligned liquid crystal display device
Abstract
A multi-domain vertically aligned liquid crystal display device
includes a first substrate, a second substrate, and a liquid
crystal layer interposed between the first substrate and the second
substrate. The first substrate is provided with a plurality of gate
lines, data lines and storage capacitor electrodes. Each pixel
region of the display device is provided with at least one storage
capacitor line, and the protrusion structure is formed to overlap
the gate lines, the data lines, and the storage capacitor lines in
each pixel region.
Inventors: |
Kuo; Chien-Chung; (Feng Yuan
City, TW) ; Liu; Chin-Chang; (Feng Yuan City,
TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
WINTEK CORPORATION
|
Family ID: |
38292357 |
Appl. No.: |
11/634294 |
Filed: |
December 6, 2006 |
Current U.S.
Class: |
349/129 ;
349/38 |
Current CPC
Class: |
G02F 1/133753 20130101;
G02F 1/133707 20130101; G02F 1/136286 20130101; G02F 1/133776
20210101 |
Class at
Publication: |
349/129 ;
349/38 |
International
Class: |
G02F 1/1337 20060101
G02F001/1337; G02F 1/1343 20060101 G02F001/1343 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2006 |
TW |
095208587 |
Claims
1. A multi-domain vertically aligned liquid crystal display device,
comprising: a first substrate provided with a plurality of gate
lines, data lines and storage capacitor electrodes, wherein each
two adjacent gate lines are intersected with two adjacent data
lines to define a pixel region, and each pixel region is provided
with at least one storage capacitor electrode; a second substrate
facing the first substrate and provided with a common electrode; a
liquid crystal layer having negative dielectric anisotropy
interposed between the first substrate and the second substrate;
and a protrusion structure formed to overlap the gate lines, the
data lines, and the storage capacitor electrode in each pixel
region to regulate the orientation of liquid crystal molecules to
create multiple domains.
2. The liquid crystal display device as claimed in claim 1, wherein
the protrusion structure includes multiple strip-shaped protrusion
sections, and the storage capacitor electrode is line-shaped.
3. The liquid crystal display device as claimed in claim 2, wherein
the line-shaped storage capacitor electrode divides each pixel
region into a first and a second sub-regions, the protrusion
sections provided in the first sub-region are substantially
parallel to the data lines and induce a first and a second slanting
directions of liquid crystal molecules, and the protrusion sections
provided in the second sub-region are substantially parallel to the
gate lines and induce a third and a fourth slanting directions of
liquid crystal molecules.
4. The liquid crystal display device as claimed in claim 1, wherein
the protrusion structure is made from photoresist or polyimide
resin.
5. The liquid crystal display device as claimed in claim 1, wherein
the protrusion structure is formed on both of the first and the
second substrates.
6. The liquid crystal display device as claimed in claim 5, wherein
the storage capacitor electrode is line-shaped and substantially
parallel to the gate lines to divide the pixel region into a first
and a second sub-regions, and the orientation of the liquid crystal
molecules in each sub-region is divided into two mutually different
directions.
7. The liquid crystal display device as claimed in claim 6, wherein
the protrusion structure includes three strip-shaped sections in
the first sub-region substantially parallel to the data lines and
three strip-shaped sections in the second sub-region substantially
parallel to the gate lines.
8. The liquid crystal display device as claimed in claim 7, wherein
the middle section of the three strip-shape sections is formed on
the second substrate, and other two strip-shape sections are formed
on the first substrate.
9. The liquid crystal display device as claimed in claim 1, wherein
the common electrode is provided with openings.
10. The liquid crystal display device as claimed in claim 9,
wherein the storage capacitor electrode is line-shaped and
substantially parallel to the gate lines to divide the pixel region
into a first and a second sub-regions, the protrusion structure is
provided in the first sub-region to induce a first and a second
slanting directions of liquid crystal molecules, and the openings
are provided in the second sub-region to induce a third and a
fourth slanting directions of liquid crystal molecules.
11. The liquid crystal display device as claimed in claim 9,
wherein the protrusion structure includes multiple strip-shaped
protrusion sections, and the openings are strip-shaped.
12. The liquid crystal display device as claimed in claim 11,
wherein each strip-shaped opening is formed between two
strip-shaped protrusion sections.
13. The liquid crystal display device as claimed in claim 9,
wherein the openings are formed overlapping the protrusion
structure.
14. A multi-domain vertically aligned liquid crystal display
device, comprising: a plurality of pixels, wherein each pixel is
provided with at least one storage capacitor electrode and a gap is
formed between two adjacent pixels; and a plurality of protrusion
structures formed to at least overlap each gap and each storage
capacitor electrode to regulate the orientation of liquid crystal
molecules to create multiple domains.
15. The liquid crystal display device as claimed in claim 14,
wherein each protrusion structure includes multiple strip-shaped
protrusion sections, and each storage capacitor electrode is
line-shaped and divides each pixel into a first and second
sub-regions.
16. The liquid crystal display device as claimed in claim 15,
wherein the protrusion sections provided in the first sub-region
are substantially parallel to the data lines and induce a first and
a second slanting directions of liquid crystal molecules, and the
protrusion sections provided in the second sub-region are
substantially parallel to the gate lines and induce a third and a
fourth slanting directions of liquid crystal molecules.
17. The liquid crystal display device as claimed in claim 14,
wherein the common electrode is provided with openings.
18. The liquid crystal display device as claimed in claim 17,
wherein the protrusion structure includes multiple strip-shaped
protrusion sections, and the openings are strip-shaped.
19. The liquid crystal display device as claimed in claim 18,
wherein each strip-shaped opening is formed between two
strip-shaped protrusion sections.
20. The liquid crystal display device as claimed in claim 17,
wherein the openings are formed overlapping the protrusion
structure.
Description
BACKGROUND OF THE INVENTION
[0001] (a) Field of the Invention
[0002] The invention relates to a multi-domain vertically aligned
liquid crystal display (MVA LCD) device having a high aperture
ratio.
[0003] (b) Description of the Related Art
[0004] Nowadays, a vertically aligned (VA) mode liquid crystal
display (LCD) is widely used since it provides a much higher
contrast than the twisted nematic (TN) mode and is superior to the
TN mode in terms of viewing angle characteristic.
[0005] FIG. 1 shows a plan view illustrating a conventional
vertically aligned LCD 100, and FIG. 2 shows a cross-sectional view
of the vertically aligned LCD, taken along line A-A'.
[0006] Referring to FIG. 1, a plurality of gate lines 102 are
arranged extending in the lateral direction, and a plurality of
data lines 104 are arranged extending in the lengthwise direction,
with each two adjacent gate lines 102 intersected with two adjacent
data lines 104 to define a pixel region on which a pixel electrode
108 is formed. Further, a storage capacitor line 106 is formed
extending in the lateral direction between two adjacent gates lines
102. In the pixel region, first sequences of protrusions 112 and
second sequences of protrusions 114 are formed in a zigzag manner,
and each corner of each sequence of protrusions overlap the gate
line 102 or the storage capacitor line 106. The first sequences of
protrusions 112 are formed at regular intervals along the lateral
direction, and each second sequence of protrusions 114 are provided
between two adjacent first sequences of protrusions 112 and stretch
in a like manner as the first one.
[0007] Referring to FIG. 2, the first and second sequences of
protrusions 112 and 114 are respectively provided on an array
substrate 110 and a color filter substrate 120. A vertical
alignment film 116 is formed overlying the protrusions, and a
liquid crystal layer 118 having negative dielectric anisotropy is
interposed between the array substrate 110 and the color filter
substrate 120. When no voltage is applied, the liquid crystal
molecules 122 near the inclined surfaces orientate vertically to
the inclined surfaces to have different degrees of tilt angles. In
case the tilted liquid crystal molecules exist, surrounding liquid
crystal molecules are tilted in the directions of the pre-tilt
liquid crystal molecules when a voltage is applied. Thus, the
orientation of the liquid crystal molecules within a unit pixel is
divided into four mutually different directions, because each
sequence of protrusions provide two different inclined surfaces and
are bent to proceed in two mutually perpendicular directions.
[0008] However, though the zigzagged sequences of protrusions may
regulate the orientation of liquid crystal molecules to define
multiple domains, their zigzag distribution on pixel regions may
occupy too much active display areas (light-transmitting areas) of
an array substrate to considerably decrease the aperture ratio for
a VA mode liquid crystal display.
BRIEF SUMMARY OF THE INVENTION
[0009] Hence, an object of the invention is to provide a
multi-domain vertically aligned liquid crystal display device
having a high aperture ratio.
[0010] According to the invention, a multi-domain vertically
aligned liquid crystal display device includes a first substrate, a
second substrate, and a liquid crystal layer interposed between the
first and the second substrates. The first substrate is provided
with a plurality of gate lines, data lines and storage capacitor
electrodes, where each two adjacent gate lines are intersected with
two adjacent data lines to define a pixel region, and each pixel
region is provided with at least one storage capacitor electrode.
The second substrate faces the first substrate and is provided with
a common electrode. A protrusion structure is formed to overlap the
gate lines, the data lines, and the storage capacitor electrode in
each pixel region. The protrusion structure may include multiple
strip-shaped protrusion sections, and the storage capacitor
electrode may be line-shaped.
[0011] Through the design of the invention, a large part of the
protrusion structures for regulating the orientation of liquid
crystal molecules are formed overlapping the gate lines, the data
lines and the storage capacitor lines, which are made from opaque
metallic films and naturally constitute the non-active display
areas (non light-transmitting areas) of an array substrate. Hence,
since a large part of the protrusion structures are placed in the
non-active display areas of an array substrate, a higher aperture
ratio is obtained compared with the conventional zigzagged
protrusion design.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows a plan view illustrating a conventional
vertically aligned liquid crystal display, and FIG. 2 shows a
cross-sectional view of the vertically aligned liquid crystal
display, taken along line A-A'.
[0013] FIG. 3 shows a plan view illustrating a multi-domain
vertically aligned liquid crystal display device according to an
embodiment of the invention.
[0014] FIG. 4A shows a cross-sectional view illustrating the
arrangement of the protrusion sections in the upper sub-region,
taken along line B-B' of FIG. 3.
[0015] FIG. 4B shows a cross-sectional view illustrating the
arrangement of the protrusion sections in the lower sub-region,
taken along line C-C' of FIG. 3.
[0016] FIG. 5A shows a schematic view illustrating the slanting
directions of liquid crystal molecules in the upper sub-region.
[0017] FIG. 5B shows a schematic view illustrating the slanting
directions of liquid crystal molecules in the lower sub-region.
[0018] FIG. 6 shows a schematic plan view illustrating the slanting
directions of liquid crystal molecules in a unit pixel according to
the invention.
[0019] FIG. 7 shows a plan view illustrating an arrangement of
multiple pixels according to the invention.
[0020] FIG. 8 shows a plan view illustrating another embodiment of
the invention.
[0021] FIG. 9 shows a plan view illustrating another embodiment of
the invention.
[0022] FIG. 10 shows a plan view illustrating another embodiment of
the invention.
[0023] FIG. 11 shows a plan view illustrating another embodiment of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] FIG. 3 shows a plan view illustrating a multi-domain
vertically aligned liquid crystal display device 10 according to an
embodiment of the invention.
[0025] Referring to FIG. 3, a plurality of gate lines 12 are
arranged extending in the lateral direction, and a plurality of
data lines 14 are arranged extending in the lengthwise direction,
with each two adjacent gate lines 12 intersected with two adjacent
data lines 14 to define a pixel region on which a pixel electrode
16 is formed. The pixel electrode 16 may be made from indium tin
oxide (ITO) or indium zinc oxide (IZO) transparent conductive
films, and a thin film transistor (TFT) 18 is formed in the
vicinity of each intersection of the gate lines 12 and the data
lines 14. Further, a line-shaped storage capacitor electrode 22
(hereinafter referred to as a storage capacitor line 22) is formed
to extend in the lateral direction between two adjacent gates lines
12.
[0026] As shown in FIG. 3, the storage capacitor line 22 divides
one pixel region into two parts, the upper sub-region 10a and the
lower sub-region 10b. According to this embodiment, each pixel
region is provided with a protrusion structure that includes a
first protrusion 24 and a second protrusion 26. The first
protrusion 24 including protrusion sections 24a, 24b, 24c and 24d
is formed on an array substrate, and the second protrusion 26
including protrusion sections 26a and 26b is formed on a color
filter substrate. The protrusion sections are strip-shaped and
extend lengthwise or laterally in a unit pixel; in other words, the
protrusions sections extend in a direction parallel to the gates
lines 12 or the data lines 14. Note that each first protrusion 24
is indicated by slant hatched lines descending from upper-left to
lower-right, and each second protrusion 26 is indicated by slant
hatched lines descending from upper-right to lower-left.
[0027] In each first protrusion 24, the protrusion sections 24a and
24b extending in the lengthwise direction overlap the data lines
14, the protrusion section 24c extending in the lateral direction
overlaps the storage capacitor line 22, and the protrusion section
24d extending in the lateral direction overlaps the gate line 12.
In comparison, in each second protrusion 26, the protrusion section
26a extending in the lengthwise direction is provided in the middle
of the upper sub-region 10a and between the protrusion sections 24a
and 24b, and the protrusion section 26b extending in the lateral
direction is provided in the middle of the lower sub-region 10b and
between the protrusion sections 24c and 24d. The protrusion
structure may be made from photoresist or polyimide resin.
[0028] FIG. 4A shows a cross-sectional view illustrating the
arrangement of the protrusion sections in the upper sub-region 10a,
taken along line B-B' of FIG. 3.
[0029] Referring to FIG. 4A, a dielectric gate insulation layer 34
is formed on the transparent substrate 32 of the array substrate
30, and the data lines 14 are formed on the gate insulation layer
34. A dielectric passivation layer 36 is formed overlying the gate
insulation layer 34 and the data lines 14, and a pixel electrode 16
is formed on the passivation layer 36. A vertical alignment film 38
covers the lengthwise-extending protrusion sections 24a and 24b
that overlap the data lines 14. Further, in the color filter
substrate 40, a common electrode 44 is formed overlying an entire
surface of a transparent substrate 42, and the lengthwise-extending
protrusion section 26a is formed on the common electrode 44 and
covered with a vertical alignment film 46. A liquid crystal layer
50 having negative dielectric anisotropy is interposed between the
array substrate 30 and the color filter substrate 40. According to
this embodiment, the lengthwise-extending protrusion sections 26a,
24a, and 24b divide the orientation of the liquid crystal molecules
into azimuths that are mutually different; that is, the orientation
of the liquid crystal molecules within the upper sub-region 10a is
divided into two slanting directions, as shown in FIG. 5A.
[0030] FIG. 4B shows a cross-sectional view illustrating the
arrangement of the protrusion sections in the lower sub-region 10b,
taken along line C-C' of FIG. 3.
[0031] Referring to FIG. 4B, the laterally-extending gate line 12
and the storage capacitor line 22 are formed on the transparent
substrate 32 of the array substrate 30. The laterally-extending
protrusion sections 24c and 24d, which are covered with a vertical
alignment film 38, respectively overlap the storage capacitor line
22 and the gate line 12. The laterally-extending protrusion section
26b is formed on the common electrode 44 and covered with a
vertical alignment film 46. According to this embodiment, the
laterally-extending protrusion sections 26b, 24c, and 24d
lengthwise divides the orientation of the liquid crystal molecules
into azimuths that are mutually different; that is, the orientation
of the liquid crystal molecules is divided into two slanting
directions within the lower sub-region 10b, as shown in FIG. 5B.
Note that the sectional views shown in FIG. 5A and FIG. 5B are
obtained by cutting a liquid crystal cell along mutually
perpendicular directions.
[0032] Hence, as seen in FIG. 6, the orientation of the liquid
crystal molecules within the upper sub-region 10a is divided into
two directions M and M', and the orientation of the liquid crystal
molecules within the lower sub-region 10b is divided into another
two directions N and N'. Consequently, according to the design of
the invention, the orientation of the liquid crystal molecules
within a unit pixel can be divided into four mutually different
directions; that is, a four-domain profile of a liquid crystal cell
is created.
[0033] FIG. 7 shows a plan view illustrating an arrangement of
multiple pixels according to the invention. Referring to FIG. 7, it
is clearly seen most of the protrusion sections (i.e. the
protrusion sections contained in the first protrusions 24) for
regulating the orientation of liquid crystal molecules are formed
overlapping the gate lines 12, the data lines 14, and the storage
capacitor lines 22, which are all made from opaque metallic films
and naturally constitute the non-active display areas (non
light-transmitting areas) of an array substrate. Hence, since most
of the protrusion sections are placed in the non-active display
areas of an array substrate (the gap formed between two adjacent
pixels and the occupied areas of the storage capacitor lines 22)
according to the invention, a higher aperture ratio is obtained
compared with the conventional zigzagged protrusion design.
[0034] FIG. 8 shows a plan view illustrating another embodiment of
the invention. Referring to FIG. 8, after the storage capacitor
line 22 divides a pixel region into an upper sub-region 10a and a
lower sub-region 10b, the three laterally-extending protrusion
sections 26b, 24c, and 24d may be formed in the upper sub-region
10a, while the three lengthwise-extending protrusion sections 26a,
24a, and 24b may be formed in the lower sub-region 10b.
[0035] FIG. 9 shows a plan view illustrating another embodiment of
the invention. According to this embodiment, the electrodes may be
additionally provided with openings to induce fringe electrical
fields, and the electrode openings and the protrusion structures
may cooperate to regulate the orientation of liquid crystal
molecules to create multiple domains. Referring to FIG. 9, for
example, the openings 54a and 54b are provided instead of the
protrusion sections 26a and 26b on the common electrode 44 shown in
FIG. 4A to achieve the same effect of forming multiple domains.
Further, the openings may be strip-shaped, as shown in FIG. 9.
[0036] FIG. 10 shows a plan view illustrating another embodiment of
the invention. During the fabrication of an array substrate, a gap
is naturally formed between two pixels (i.e. between two adjacent
pixel electrodes), such as the gap 54c or the gap 54d shown in FIG.
10, and the gaps 54c and 54d also allow to produce fringe electric
fields. Thus, in this embodiment, the upper sub-region 10a is
provided with only one opening 54e on the common electrode, and the
opening 54e together with the pixel gaps 54c and 54d may replace
the lengthwise-extending protrusions to achieve the same effect of
forming multiple domains.
[0037] Alternatively, as shown in FIG. 11, the electrode openings
54f and 54g are additionally formed and overlap the protrusion
sections 26a and 26b to further enhance the strength for slanting
the liquid crystal molecules.
[0038] While the invention has been described by way of examples
and in terms of the preferred embodiments, it is to be understood
that the invention is not limited to the disclosed embodiments. On
the contrary, it is intended to cover various modifications and
similar arrangements as would be apparent to those skilled in the
art. Therefore, the scope of the appended claims should be accorded
the broadest interpretation so as to encompass all such
modifications and similar arrangements.
* * * * *